This study is an epidemiologic analysis of the relationship between a potential teratogen, marihuana, pregnancy course and outcome. The effects of exposure during pregnancy will be measured both in the immediate postnatal period and during early developmental stages. The proposed design is a prospective evaluation of the experience of pregnant teenagers. Women age 18 through 20 who attend the prenatal clinic at Magee-Womens Hospital will be interviewed pre and postnatally. Babies will be examined at birth, and at 2 weeks and 8 months of age. Measures of infant outcome will include physical status, growth, infant state and development. Specific attention is focused on maternal psychological status as an important correlate of marihuana use, pregnancy outcome and infant behavior. The confounding effects of other drugs, physical status and life style of the mother will be controlled.